Constant speed propeller



March 7, 1950 R. w. JENNY 2,499,826

CONSTANT SPEED PROPELLER Filed Nov. 14. 1945 hunted Mu.' 7, 195o commsneu nomma Robert W. Jenny, lut Paterson,

Curtiss-Writht Corpora N. J., alimento Bloomfield, N. J.,

a corporation of Delaware Application November 14, ms, seran Nn. szssss4 Cllllna. (Cl. PIF-160.18)

1 The invention relates in general to an improvement in constant speedaircraft propellers, and specincally relates to an improved form ofpropeller assemblyoi the type in which the pitch I of its associatedblades is set at some preselected angle best suited for emcientoperation vat normal engine speed.

The primary object of the invention is to maintain a constant propellerspeed despite the momentary presence of forces, such as variations inengine speed orv vehicle speed as in diving, and which force factors ofcourse tend to vary the continuity of the desired preilxed propellerspeed.

Broadly this objective is obtained by utilizing variations in the pitchof the propeller blades imposed thereon by variations in propellerspeeds either by variations in engine speed or by windmilling, as acontrol for automatically increasing the pitch angle so as to slow downthe propeller speed when overspeeding, and for decreasing the pitchangle to increase propeller speed when underspeeding.

Still another object of the invention is to provide a simple form ofpropeller assembly which will contain within itself all the mechanismnecessary to effect the requisite corrective change in pitch to imposeor release an increment of load on the propeller blades as may benecessary to maintain the propeller speed` at the desired constant, andin this connection to provide a composite unit complete in 'itself anddesigned to be mounted conventionally on any engine shaft.

Various other objects and advantages of the invention will be in partobvious from an inspection of the accompanying drawings and in part willbe more fully set forth in the `follov'ving particular description ofone form of device embodying the invention, and the invention alsoconsists in certain new and novel features 'of construction andcombination of parts hereinafter set forth and claimed.

' in the accompanying drawings:

Fig. l is a View largely in perspective showing a preferred embodimentof the invention mounted on an airplane engine;

Fig. 2 is an enlarged view partly in side elevation looking at the rightside of `Fig. l and partly in vertical section taken axially of Itheengine shaft; y

Fig. 3 is a verticalsectionvlew taken onza planek offset from the'sectional' .'part .of- Fig...;2 and taken on theline 3--3 of Fig.1;.and

Fig. 4 vis an enlargedsectionalldetailof.aportion of Fig. 3 showingvalve port arrangement.

In the drawings there is disclosed a part of an airplane engine Aincluding its nose section B and which engine is provided with an engineshaft C of conventional design. It is herein intended in general thatthe engine be of any known type and not necessarilyan airplane engine.Mounted on the engine shaft is a propeller assembly l0 which constitutesthe novel feature of the disclosure and in eiect forms an attachment to`the engine. The assembly includes a long hub Il demountably secured tothe engine shaft by splines l2 and nut not shown and otherwise arrangedto turn therewith following conventional practices in this respect. Thepropeller assembly includes a central body portion I3 from whichprojects a pair of outstanding tubular receptacles I4 and I5 extendingdiametrically of each other as shown in Fig. 1. As each receptacle andits associated parts are identical in structure and function, thedetailed description of one will iit the other. Mounted in eachreceptacle is a propeller blade I 6, the intruded end of each of whichis contained vin a metal socket I1 and conventionally mounted in eachcase respectively in outer bearings l8 and inner bearings i9 to permitturning oi' each blade about its long axis a-b, and thus obtainvariations in the pitch angle of each of theblades. `For the purpose oiturning the blade the metal socket is provided with a pair ofoutstanding crcumferentially spaced apart projections 20 and 2l betweenwhich operates a roller 22 rotating on a stud 23 projectinglaterallyfrom a nut 24 mounted on a threaded shaft 25 as more particularly shownin Fig. 3. The arrangement is such that when the nut moves from itscentral position as shown in Fig. 3 towards the left by reason of therotation of shaft 25 in one direction, the pitch of the associated bladeis increased, while a movement of the nut to the right of its normalcentered position by reason of the rotation of the shaft in acontra-direction will cause the angle of the blade to decrease from itsnormal pre-set angle. The threaded shaft 25 telescopes" and is securedby pin 2S to a main shaft `-ilmounted for rotary movement in a hollowcasing 28 forming an integral exten- .sionprojecting from the bodyvportion i3 as best shown in Fig. l. The two casings 28. are shown inFig. 1 in balanced relation'on opposite sides of the body. portion, anddiagonally related each adiacez'itits.l associated propeller blade. Theforward' end lof shaft 2l is. mounted in anadjustalf1-beariig'28carried'in the'front wall 3l Aof l readily mountedthe casing 23. The right end of the main shaft 21 proiects'exteriorly ofthe casing through its rear wall towards the engine and terminates; in aspur gear pinion 3| disposed to be rotated both clockwise andanti-clockwise as hereinafter indicated to shift the nut right and lefton its threaded shaft 23 as above indicated.

Located between the propeller assembly as thus far described and thenose section B of the engine casing is a hollow housing 32 of annularform ntted to and carried by an inward extensionl 33 of the hub Il andcoacting with the propeller assembly to form a complete unit on andremovable from theongine shaft.

The housing 32 includes a rear flat closure wall 34 and a rugged outercylindrical rim 33 fitted into a recess 33 provided therefore in therear face of the body portion |3. An oil ring 31 is iltted between rim33 and the wall outlining the recess to avoid oil leakage out of theassembr. A long bearingwall 33 integral with the rear wall 34 forms theinner perimeter of the housing 32 and a long plain bearing 33 isinterposed between the same and the hub extension 33. The housing issecured from rotation and held fixed in space by means of one or moremounting brackets 43 securing it to the engine casing of the engine nosesection.

Secured to the body portion |3.- encircling the extension 33 of the huband projecting into the housing 32 is a large driving gear 4| foroperating an -ar pump 42 and for operating a centrifugal governor 43hereinafter described.

The air pump as shown in Fig. 2 is of conventional design and includesan actuating shaft 44 provided with a pinion 43 at all times meshingwith the gear 4|. So long as the propeller assembly is turning the pump42 provides a constantly available source of air pressure for actuatinga pair of expandable brakes by the selective action of a speed controlvalve hereinafter described and in turn controlled by the ball governor43.

The wall 34 of the housing 32 is also provided with a pair of inwardlyprojecting wide flanges forming a pair of concentric brake drums, thatis an outer drum 41 and an inner drum 43. An outer expandable brake 49is located between the outer drum 41 and a drum-like flange 33 pro-Jecting from s. large internal gear 3i fitted axially v l -4 eithergear3|orllxnaybeheldfromrotation selectively while the rotation of thepropeller operating throughpinion 3l, main shaft 21 and threaded shaft23 will cause the nut 24 to move right or left onthe threaded shaftdepending upon which of the expandable brakes is in selective clutchingposition at the moment.

The selective actuation of either brake 43 or 33 is dependent on thespeed of rotation of the propeller assembly acting through the drivinggear 4I. The gear 4| meshes with pinion 31 on governor shaft 33 whichextends as shown in Fig. 3 through a valve chamber 33 formed in thehousing and has its end Journalled in an adjustable nut 33 threaded intoa closure plate 3| at the open end of the chamber. A valve 32 isslidably mounted in the chamber and at its outer side provides a conicalsurface 33 engaged by a plurality of balls forming the centrifugalgovernor 43. A stop plate 34 pinned to the shaft coacts with the bevelsurface 33 to form a wedge space to accommodate the balls 43. A spring33 reacts between the nut 33 and the valve and is biased to shift thevalve to the left of the showing in Fig. 3 when the governor is freefrom centrifugal force and the balls collapsed towards the shaft betweenthe wall 34 and the bottom of the recess 33. A roller bearing 32 rideson the flange 53 between the same and the outer rim 35. Gear 3| is atall times in mesh with spur gear pinion 3| as best shown in Fig. 3. Theparts are so organized that when the brake 43 is expanded by means ofthe admission thereto of compressed air from the pump 42, the gear 3| isclutched to the housing 32, is thus restrained from rotating whilepermitting pinion 3| to revolve about the fixed track provided by thegear 3| -when so locked to the engine casing.

Similarly there is disposed between the inner drum 43 and the flangeforming the bearing wall 33 of the housing, an inner expandable brake33. the flange 34 of a relatively small external gear 33 and rollerbearing 33, all fitting axially between the wall 34 and the body portionI3.V Gear 33 is at all times in mesh with the spur gear pinion 3| asshownin Fig. 3 and functions as above described for gear 3|. These partsare so organized that with the expansion of the brake 33 the gear 33 isfixed to the housing and held thereby from rotation. Fromthis commotionit is seen that 33. 'Ihe valve 32 is provided at its perimeter with anannular channel 33 and in the position shown in Fig. 3 the valve is in amiddle position shutting oi! fluid communication between the air pump 42and both of the expandable brakes and is the position assumed by thevalve when the engine shaft is turning at the desired normal drivingspeed.

The wall outlining the valve chamber 33 is provided with three ports-31,33 and 13, the ports 31. 33 and 31, 13 being communicable at times byregistry therewith of the groove 33 in the governor actuated valve 32.The air pump 42 (Fig. 2) delivers its output through a conduit. notshown, to the air supply port 33 and thence to the middle valve port 31.The left port 33 is in open uid communication with the outer brake 43through a passageway 1| and the right port 13 is similarly incommunication with the inner brake 33 through a passageway 12 in thewall which outlines the chamber 33.

In operation and assuming that the engine is turning its shaft at itsdesired or normal speed, then the ball governor by reason of thepresetting of tension on the spring 33 by the manipulation of the nut 33will be in the intermediate position and the valve in its mid-positionshown in Fig. 3, and in this position there will be no sir pressureacting on either of the expansible brakes. In the event the engine shaftoverspeeds for any reason the ball governors will of course moveoutwardly by centrifugal action from their preset position shown in Fig.3 thus shifting the valve to the right of the position shown. Thisplaces the air pump in fluid communication with the right port 13 tointroduce air pressure into the outer drum to clutch the gear 3| infixed relation to the engine casing. With gear 3| so held from rotationin space the continued rotation of the propeller assembly acts to drivepinion 3l and shafts 21-23 in the direction to cause nut 24 to increasethe pitched angle of both of the blades On the other hand, assuming thatthe speed of the engine is for the moment below the preset engine speed,then the ball governors will tend to further collapse from their normalintermediate position shown in Fig. 3 inwardly towards the shaft 58 thuspermitting spring 65 to move the valve further to the left from theposition shown in Fig. 3 thus placing the left port 69 in communicationwith the air pump. This resetting of the valve opens pressure to theinner brake 53 and forces the same into clutching engagement with thegear 55 to cause it to be fixed in space and thus permit the pinion 3|to ride about the gear 55 as above indicated. This rotates the threadedshaft in the opposite rotary direction, that is in a direction to reducethe pitch of the blades I6. With'this reduction in pitch of blades thereis attained a corresponding reduction in the load imposed on the bladesthus permitting the blades to speed up until the engine shaft isrotating at the speed at which these several controls have been set andunder which condition both brakes are inoperative and the parts restoredto their normal operative position as shown in the several figures ofthe drawing.

By varying the tension imposed on the spring 65 by suitably advancing orretarding nut 60, the governor may be adjusted as desired and in thisway the speed of the engine shaft may be eventually set at that speed atwhich the engine functions most eiiiciently.

It is a particular feature of this disclosure that all of the controlsfor maintaining the engine shaft at its constant speed is contained inand forms a readily demountable part of the propeller assembly. It isthus possible to replace the propeller and the controls therefor withoutdisturbing any other part of the engine construction.

I claim:

1. A propeller assembly for mounting on a power shaft including a bodyportion rotatable with the shaft, a propeller blade rotatably mounted inthe body portion for adjusting its pitch angle, means for adjusting thepitch angle of the blade, said means including a pinion and a shaftoperatively connected to the pinion and blade, a pair of gears each inmesh with the pinion and normally running idle, a pair of pneumaticallyexpandable brakes, one for each gear and engageable therewith, a sourceof compressed air for expanding the brakes to engage said gears, a valvefor selectively causing either `brake to become operative, a governoractuated by the speed of the rotating assembly and operatively connectedto the valve to cause the same to open one of the brakes to said sourcewhile intercepting communication between the source and the other brake,and a non-rotatable casing journalled on said propeller body portion,housing said gears, brakes, air source, valve and governor, said casingproviding reaction means for said brakes when the latter are energized.

2. A propeller assembly for mounting on a power shaft including a hubrotatable with the shaft and having blade sockets, blades mounted insaid sockets for pitch changing, a mechanism on the hub for changingblade pitch including a member movable relative to the hub. a casingjournalled on the hub and fixed against rotation, a governor, having avalve operable in response to speed errors, in said casing driven byrotation of said hub relative to the casing, means wholly within saidcasing and controlled by governor valve movement to actuate said movablemember for changing blade pitch, said latter means comprising a pair ofnon-rotating brake elements, fluid means controlled by the governorvalve for pressurizing one or the other of said brake elements withfluid, and normally freely rotatable` drums within said casing andoperatively connected to said movable member, said drums beingengageable by said brake elements when pressurized, to restrict rotationof said drums.

3. A propeller assembly for mounting on a power shaft including a hubrotatable with the shaft, having blades mounted therein for pitchchange, a casing journalled on the hub and secured against rotationtherewith, gearing, including a pair of normally free turning brakedrums rotatable with the propeller, connected to said blades foreffecting changes in the pitch of the blades in response to reduction inthe speed of one or the other of said brake -drums below propellerspeed, brake elements anchored in 'said casing inflatable selectively toengage and slow one or the other of said brake drums, a governor havinga valve operated thereby and connected to said brake elements, and afluid pressure source for inating said brake elements through and byoperation of said valve.

4. A propeller assembly for mounting on a power shaft including a hubrotatable with the shaft having blades mounted therein for pitch change,a casing journalled on the hub and secured against rotation therewith,gearing, including a pair of normally free turning brake drums rotatablewith the propeller, connected to said blades for effecting blades inresponse to reduction in the speed of one or the other of said brakedrums below propeller speed, brake elements anchored in said casinginflatable selectively to engage and slow one or the other of said brakedrums, a governor having a valve operated thereby and connected to saidbrake elements, and a fluid pressure source for inflating said brakeelements through and by operation of said valve, said governor and fluidpressure source being driven by said propeller and being containedwithin said casing.

ROBERT W. JENNY.

REFERENCES CITED UNITED STATES PATENTS are of record in the Number NameDate 2,007,417 Aivaz July 9, 1935 2,138,339 Chauviere Nov. 29, 19382,184,143 Hoover Dec. 19, 1939 2,229,058 Dicks Jan. 21, 1941 2,250,694Algarsson July 29, 1941 FOREIGN PATENTS Number Country Date 517,870Great Britain Feb. 12, 1940 changes in the pitch of the`

